1. Field of the Invention
The present invention relates to a negative-tone radiation-sensitive resin composition.
2. Discussion of the Background
In recent years, the degree of integration and the number of layers of large-scale integration (LSI) used for electronic instruments (e.g., mobile phone) have rapidly increased. Therefore, a multi-pin mounting method has been required to mount LSI on an electronic instrument. For example, bare-chip mounting using tape automated bonding (TAB) or flip-chip bonding has attracted attention. In this case, it is necessary to accurately dispose a bump electrode (bump) (i.e., connection terminal) on LSI.
Various precision parts (e.g., bump) are produced by applying a radiation-sensitive resin composition to the surface of a workpiece to form a resin film, patterning the resin film by photolithography, and performing electroplating or the like using the patterned film as a mask (see Japanese Patent Application Publication (KOKAI) No. 2006-285035 and Japanese Patent Application Publication (KOKAI) No. 2007-293306, for example).
When producing various precision parts (e.g., bump) using photolithography, technology that forms resin films that differ in thickness is required. A radiation-sensitive resin composition is normally applied to the surface of a workpiece (e.g., substrate) by spin coating.
When forming a resin film having a given thickness by spin-coating a radiation-sensitive resin composition onto a substrate, it is necessary to strictly set the spin coating conditions (e.g., the rotation speed of the substrate, the rotation time of the substrate, and the concentration of the radiation-sensitive resin composition).
For example, when it is desired to form resin films that differ in thickness to a large extent, it is necessary to set the spin coating condition before and after applying the radiation-sensitive resin composition. Since the rotation speed of the substrate can be easily changed, resin films that differ in thickness have been normally obtained by changing the rotation speed of the substrate. It is also possible to form resin films that differ in thickness by changing the rotation time of the substrate.
In recent years, the size of a substrate has increased in order to improve yield. However, spin coating has a problem in that it is difficult to increase the range of rotation speed of the substrate as the size of the substrate increases. Therefore, it may be difficult to form resin films that differ in thickness to a large extent using an identical radiation-sensitive resin composition by changing the rotation speed of the substrate.
When forming resin films that differ in thickness using the radiation-sensitive resin composition disclosed in Japanese Patent Application Publication (KOKAI) No. 2006-285035 or Japanese Patent Application Publication (KOKAI) No. 2007-293306, the resulting resin films may have an almost equal thickness when fired after spin coating.
Specifically, it has been difficult to form resin films that differ in thickness to a large extent by spin-coating a related-art radiation-sensitive resin composition.